and we--we're trapped here, Andy. No wonder
that man said it was the last time. We're trapped by the rising tide!"

CHAPTER XXI

DEATH IS NEAR

"Frank, are you there?"

"Yes, Andy. Give me your hand."

The two brothers spoke softly. It was in the darkness of the cave, for
they had both released the pressure on the springs of their portable
lights to make the little dry batteries last as long as possible. It
was several minutes after the first awful discovery of the incoming
tide, and they had maintained a silence until the younger lad, unable
to longer endure the strain, had called out.

Silently they clasped hands in the blackness.

"Frank, do you--do you think there's any way out?"

"Why, of course there is, Andy. All we've got to do is to wait a
while, and someone will surely come to our rescue. Father and mother
know we started for this island, and if we don't get home soon they'll
start a searching party after us."

"Yes, but the rising tide, Frank. We--we may drown."

"Nonsense. The water can't get very high in here. We'll simply go to
the highest part of the passage, and wait until the tide goes out.
That won't be so very long. What makes me mad though, is to think how
that man fooled us. That was his object all along. He wanted to get
us in here so he could drop that rock across the opening and have us
caged."

"Can't we try to get out?" asked Andy. his usually joyous spirits had
departed. He was very much subdued now, and in the momentary flash of
his light, which he permitted himself, Frank saw that his brother was
very pale.

"Of course we'll try!" exclaimed the elder lad, with all the assurance
he could put into his voice. "Perhaps we can manage it, too. Let's
have a try. It's of no use to do it here. We must go back to where he
pushed down the rock. Perhaps it isn't in as tight as we thought at
first. Come on. But don't use your light. Mine is enough, and we
must save them as long as we can."

By the gleam of the single electric torch they made their way back.
Soon they were at the rock which made them prisoners. It loomed grim
and black in the semi-darkness.

"The water's higher," said Andy, in a low voice. Frank had noticed
that, for it now reached to his ankles as he splashed his way back
along the passage. But he had said nothing, hoping Andy had not
observed it.

"Yes," said the older boy cheerfully, "It's bound to rise until the
tide is at flood,